THE PARATETHYS AT THE END OF THE EARLY-MIDDLE MIOCENE AND ITS RELATIONS WITH SURROUNDING BASINS

The Paratethys cyclic development (Andrusov, 1961; Nevesskaya et al., 1986) determined the main trend in investigating the composition and e volution of its biota, its hydrology, paleogeography, and tectonics. E ach cycle was marked by changes from marine to semimarine and brackish conditions. Incidentally, each subsequent cycle with marine or semima rine regime became increasingly shorter, while the brackish stage beca me, on the contrary, progressively longer (Nevesskaya et al., 1986).